1. Field of the Invention
The present invention relates to internal combustion engines. More particularly, the present invention relates to the use of a reentrant cylinder head for the lengthwise scavenging systems of internal combustion engines.
2. Prior Art
The well known concept of the reentrant cylinder head configuration generally consists of: the reentrant cylinder head, which provides an annular recess for the cylindrical sleeve; the cylindrical sleeve, which has openings into its wall; the cylinder, which has axially displaced ports; and the piston. The cylindrical sleeve is attached to the piston aligned to its outer margin. The ports' operation is controlled by the reciprocal movement of the sleeve, such that the port opens when the opening of the sleeve aligns with the port.
There are many previously patented reentrant cylinder head applications; the oldest one is U.S. Pat. No. 1,010,939 of G. A. Mercalf et al., the latest one is U.S. Pat. No. 2,591,619 of J. T. M. Selamann. All of those patented reentrant cylinder head applications surely have some variations, but the principal concept is the same as the one mentioned above. The prior arts of the previous inventions have some inherent drawbacks, such as the weight of the sleeve which adds to the piston and the sealing difficulty around the openings of the sleeve.